Question

What is energy?


I know that energy is the ability for a physical system to do work. But, what confuses me the most is the law of conservation! It states that energy can not! Be created nor destroyed, only transformed to one form to another...

So that means in the WHOLE universe energy is a constant number/rate?

Imagine this, I defined work: Fd or τθ

Those are clearly forces! In every system that involves transfer of energy,work being done, etc...
It just a force or multiple forces acting on a object or certain objects on a displacement...

Answer 1

I know this is a random question and not asked likely but yea, When did they start to think and prove the law of conservation? What law PROVES that energy can never be destroyed or created? I just want to know that point.

I want to find the main laws the just shuts my curiosity up!

Also before we even talk about "Thermodynamics" lets keep it for later, while discuss conservation...

Regards,

Vision,

Answer 2

Ow yea I'd like to invite some experts please help out @experimentX @waterineyes
I'll invite even more later on because I want this to be the main topic maybe of the year or something BIG!.

What do you all think of enegy?

Answer 3

sorry ... extremely sleepy right now!!

Answer 4

In my view, Saying energy can't be created or destroyed, it is better if you will say:

Energy "of a system" can neither be created ......... etc etc..

The word "system" is very important in defining that law..

Answer 5

Hmm good point @experimentX @waterineyes
However, we should look at the fundamental things because its crucial to our understanding. To build a innovative future we must also become innovative in physics! Were only starting to understand the most complex topics now :P

Answer 6

But really, I started to think about this because when you have a system that is doing work and you only increased the displacement or Force the total work is increased and the energy transfer has increased as well...

Answer 7

To relax my self from all that stress from thinking about the matter. I just said to my self "Energy" is a measuring of work... But that just contradicts a lot of things...

Answer 8

It really does...

Answer 9

But lets stay in the topic of conservation. How did they prove that energy is always conserved and how did the origin of "Energy" really start? Finally WHAT formula specifically shows that energy is always conserved? And never created nor destroyed in a system?

Answer 10

I'd like yo invite more experts/champions/mentors to this topic @jhonyy9
Please participate in this topic so as try to invite more people to join.

I only want to make people think about this matter just as I am.

Regards,

Vision.

Answer 11

@waterineyes Since you're a champion and know a lot of people whom possibly could help, could you invite them please? Much appreciated.

Answer 12

Finally I'd like to say Im not claiming anything or saying any random facts... I just want to have an open-minded discussion about this topic of "Energy".

Answer 13

@ganeshie8 @ghass1978 @ghazi @AccessDenied @eyust707

Answer 14

Thank you @waterineyes !

Answer 15

@Vincent-Lyon.Fr @mathmate @henpen

Please give your suggestions or point of view..

Answer 16

@waterineyes shall we first solve this...or try to distribute medals??

Answer 17

A main 'thing' is that energy is relative- you cannot compute the absolute energy of a system. Also, *I think* that we do know know what energy really IS (although obviously heat energy=KE), only a disparate group of values which we know to be conserved.

Answer 18

Have to go to sleep its 1:19 am here..

Hope you will get enough help @Visionary01

Here, you all should solve the problem first..

Medals, I can give to all by my hacking technique..

Ha ha ha... @ghazi

Answer 19

You can derive the conservation of energy (in a gravitational system at least) using F=ma, I think.

Answer 20

And it is implicit in any law of mechanics more generally.

Answer 21

the very fundamental principle by which you can justify principle of conservation of energy is what ever work we do on an object is stored in the form of potential energy in it ...like i through a ball in space...then till i released it from m hand i applied some force and gave it a displacement this work is stored in the ball in the form of potential energy ...now when the ball travels ...that potential energy is harnessed as the kinetic energy ....(energy of motion) similarly you can apply this on earth....and your energy remains conserved ...there are lot of examples

Answer 22

The energy - mass of a system is conserved.
E = mc^2

Answer 23

@Visionary very good question, respect.

Answer 24

But it is as you noticed a FUNDAMENTAL CENTRAL notion - so its conservation needs some use of fundamental laws. It is not axiom - thre is a proof. I will dedicate a tutorial in detail, but for now (regrettably as I dont have much time this moment) I will state the stages involved in defining energy and the establishment of its conservation in closed sytems
AS follows

Answer 25

As the asker has left - it is only fair that the explanation will be postponed to his return

Answer 26

Hallo everyone, Sorry it was a busy sunday :P

Ok, besides all the things you ALL have stated its only fair to start defining energy first and its origins as a "Theory" then a proven fact. How about that? A group "project/research" if you may...

Now @Mikael please do go on :)

Answer 27

Just to give you a point. Please, Please, Please! Be open minded and don't just reply with an immature manner. Because I have discussed this with people who I honestly find puppets of this worlds they don't ask any questions and raise doubt. In philosophical terms we should sometimes doubt and reassure ourselves with the facts.

Answer 28

With all that beings said. I'll start with my basics observations. :)

Answer 29

Now, "Energy" is it a Ability, Quantity, In terms for that what is it?
Another thing, How have they thought of it? I understood Vis Viva "Living force" was an old concept (Not used anymore).

Answer 30

What bothers me about energy is:

1) Its existence: You can prove Force,Mass,Distance, Everything is proven physically. However, ENERGY! Its hard to describe... Or invision.

Answer 31

Surprisingly, I defined energy as how? By breaking it down!

When first I looked at it and say well its the ability of work, Ok what is work? Then introduced with: Fd , τθ.

Then said to myself... Where is energy in all of this? I find it missing, not making any sense!(Personally)

Answer 32

I don't want you to think in a way that I tend to violate or any negative thing against my words... But were bound to think eventually and ask questions! And to research...

What I want to discover/uncover the mysteries of energy...

Maybe from this question I can start of somewhere...

I'll certainly include some examples to support my "Questions" But further when we understand how the "Idea" of energy developed.

Answer 33

Please continue to state you're ideas about this because I log on a few times in the day... So I'll try to reply ASAP!

Regards,

Vision.

Answer 34

@visionary01 go through this ....i am sure your notion of energy will be broadened http://profmattstrassler.com/articles-and-posts/particle-physics-basics/mass-energy-matter-etc/matter-and-energy-a-false-dichotomy/

Answer 35

Energy is something which objects can have, and groups of objects can have — a property of objects that characterizes their behavior and their relationships to one another.

Answer 36

@ghazi

In that case. Then all objects have PE, and can be converted to KE.
Now I can be a little philosophical and say "energy" can also be defined as the "Ability" for all objects to do work.

In a sense now we can't say that energy is a constant value don't you think? Maybe while universe in constantly expanding it gives birth to new "objects" that have PE & KE.

What I'm trying to do is lift limitations on certain "ideas" so we can explore more of this phenomenon.

Answer 37

@ghazi I haven't read the article yet. But I will soon.

Answer 38

@Visionary01 i am even in doubt just not only about what exactly is energy (is it real thing that could be stated only through displacement or is abstract)..?? but also how the most famous Einstein formula mass-energy equivalence could be stated how one thing that's mass that absolute physical in its sense you could measure it in kgs and you could define it like ..this is 1 kg tomato...but energy if its abstract then how could they be compared...really have a long doubt abt it!!

Answer 39

if we could relate these two one real mass and other abstract(let's say it) energy then i think more points and legendary misconceptions could be cleared out..!!

Answer 40

@ghazi i really like that article ..its quite interesting!!

Answer 41

@Visionary01 well as far as my point is concerned i just demonstrated an example that if we do work on a body that work will be stored in the form of potential energy...now it depends on the body how it utilizes it...so if it is in motion then it's K.E...now when you say about expanding universe then i guess already there is potential energy that is harnessed as KE whilst objects are separating ......@shivaniits i am glad you read it...it really gives a new insight

Answer 42

@ghazi good point.

We can say that every ATOM! In the whole universe has PE.
It was given from KE from the beginning of the universe.... (Now were going philosophically even more to the birth of all things).

Answer 43

The only thing I can easily say is that energy is simply the "ability" for any object to do work. Most objects can convert PE to KE by their own and some need KE to convert PE to KE. So yea most objects have energy in this sense that they can do work. Or simply the "ability" to do work :)

I really love were this is going! @ghazi

Answer 44

well ...if you consider big bang...then it was stored potential energy that transformed in to kinetic after the explosion...and objects started movin away

Answer 45

@ganeshie8 @dpaInc @myininaya

I'd like you all to participate in this topic please :)

Answer 46

@ghazi I only consider that the universe was created. I'm not sure what theory supports it perfectly but I will go with the flow then :P

But Yea, in this cause the universe was created with Potential energy that is stored in every object! But again if we say the PE was value at:100x100000000000000000000000000000 etc.... J of power. We certainly can say that there is a limit of energy.

Answer 47

I don't think there is a constant value for energy now... I feel its just any physical objects ability "energy" to do work... Based on what it has STORED(P.E) within :P (Hows that philosophical point) @ghazi

Answer 48

no doubt that there is limitation of energy...but how much it is ...we can't estimate it so far...so we need not to do that...but fundamentally it is....property ...of anything

Answer 49

if you ask what exactly it is...i mean if you say define energy ...then it has just one definition.....it is a property of objects that characterizes their behavior and their relationships to one another.

Answer 50

True. @ghazi

However, do you agree to this point: That energy can also be defined as the ability for every physical object to do work?

+ How do we know that energy is limited?

Answer 51

To its quantity that is...

Answer 52

well firstly if you talk about ability to do work as energy then up to a certain extent it is true....till you hold yourself to work....but like i take an example of a ball at rest there is no work done but it has energy of it too....every thing in this universe has energy ...energy is the most fundamental thing....or property
now limitation of energy is just a theory...may be it is generating somewhere which we don't know....and it is increasing every second...

Answer 53

@Visionary01 try to through the link i have mentioned ...that's really helpful and lucid

Answer 54

It's only a popularisation, but http://www.youtube.com/watch?v=7ImvlS8PLIo hypothesises as to how there could be no cap on energy.

Answer 55

@Visionary01 energy is not object in terms of physics.....though every object has energy...so your definition as ability to do work by an object has certain limitations

Answer 56

@ghazi Now I agree with you in term of beyond the "ability" of work. Its certainly true that even objects at rest has that same ability and we call it "potential energy" :)
So in term of the limitations. I honestly believe that since every object can do work... And day by day the universe is expanding create more objects that has PE. Now the expansion of the universe itself is amazingly wonderful having more energy... Its funny at the same time we can say at the beginning of the universe could possibly have brought energy.... Ah I'm losing my train of thought now too much thinking :P

@ghazi I'll read you're article and get back to you!

Answer 57

Please all participate in this discussion :)

Answer 58

"It is important to realize that in physics today, we have no knowledge of what energy is. We do not have a picture that energy comes in little blobs of a definite amount."
-Richard Feynman

Energy itself is not something you can hold, it isn't something you see, it isn't something you can hear or taste, it isn't tangible at all. It is the result of properties directly related to energy that allow us to touch, see, hear and taste.

We use the term "energy" to describe abstract values that can predict observable properties within a system. It is simply as a placeholder that is guaranteed to be balanced and accounted for.

Answer 59

Ok then. That means all physical objects has either PE or KE. And its always be conserved. Right?

I don't think its a limited constant value... However, every object that is able to do work has energy "the ability" to do so... We can't define energy properly... And sometimes when I look at forces I ask WHY DO WE need energy? We can describe so much by all the kinds of forces...

Im starting to build up my final conclusion and will share it soon!

Answer 60

energy is movement with time

Answer 61

@UnkleRhaukus Really? Thats the first time I have ever heard that definition :S

Answer 62

are you saying i dont make sense/

Answer 63

"That means all physical objects has either PE or KE. And its always be conserved. Right? "

Yes, energy is rigorously conserved and be categorized into potential energy, kinetic energy, or a combination thereof.

"I don't think its a limited constant value"

Energy, as defined by physicists, can not be created nor destroyed. Within a closed system its value IS constant.

"every object that is able to do work has energy "the ability" to do so. We can't define energy properly... "

As stated earlier energy is a scalar value assigned to certain aspects of a system. It is used to predict and account for various physical phenomena that are directly or indirectly observable.

"sometimes when I look at forces I ask WHY DO WE need energy? We can describe so much by all the kinds of forces..."

Energy is entirely different from a force. We use a force to describe a change in motion. We use energy to explain the source of observable phenomena. This could be a change in motion, yes, but it could also be a change in temperature, a change in color, a change in chemical composition, etc. Many of these things would be very difficult to model with forces -most physicists prefer to use energy.

Answer 64

if you look close enough , temperature, color, chemical composition, all have to do with movements

Answer 65

@UnkleRhaukus not all energy is associated with movement. For example consider a rock on Earth sitting height h above a ledge.
From our frame of reference it is not moving but it does have gravitational potential energy equal to mgh.

To say that "energy is movement with time" would be a bit naive. Energy is not movement at all. It is literally an abstract value, some number, we use to keep track of observable phenomena.

Answer 66

We can use energy to account for movement but it is not the movement itself.

Answer 67

@eyust707 do u mean displacement when u were talking about "We can use energy to account for movement"...??? and what if we consider the movement in temperature the movement could be heat flow....??

Answer 68

it could move down the cliff

this potential energy is



potential for movement

Answer 69

@UnkleRhaukus Yes, it COULD move down the cliff but currently is not moving. My point is that energy can be related to the ability to move and is not always used to describe the movement itself.

@shivaniits "do u mean displacement when u were talking about "We can use energy to account for movement"...???"

I am under the assumption that movement and displacement can be used interchangeably in this case. I am using movement because it is the term UNK used originally.

"what if we consider the movement in temperature the movement could be heat flow....??"

Well I believe UNK was referring to the physical movement of the molecules and not the overall movement of heat flow. However, we can use energy to account for both.

Answer 70

@eyust707 .. "physical movement of the molecules and not the overall movement of heat flow"..in case of metal block with one end at temperature higher than other....in this case which particles are moving you are referring to
1)the atoms of metal block(but it could deform its structure)
2)or the electrons ...!!

Answer 71

I do not know much about thermodynamics but in the example above I would be referring to the kinetic energy of the metal's particles. This could be kinetic energy of atoms, molecules or electrons.